Tunable/de-tunable wireless power resonator system and related methods

ABSTRACT

A wireless power transmission (WPT) system. Implementations may include a power source coupled with a first wireless power transmission (WPT) system and a load coupled with a second WPT system including a sense circuit. The second WPT system, using the sense circuit, may be configured to dynamically tune a resonance of the second WPT system with the first WPT system to a desired resonance frequency value to allow transfer of a desired voltage or a desired power to the load. The desired resonance frequency value may be less than a maximum possible resonance frequency value. The first WPT system may be capable of transmitting more voltage or more power than the second WPT system or the load can receive without inducing damage to the second WPT system or the load.

BACKGROUND 1. Technical Field

Aspects of this document relate generally to systems for powertransmission, such as wireless power transmission and/or wirelessbattery charging systems.

2. Background Art

Wireless power transfer using magnetically coupled coils is accomplishedusing both loosely coupled coils and tightly coupled coils (i.e., in atransformer). Loosely coupled coils do not have a common magnetic coreand so use magnetic flux generated by the coil connected to the powersource to inductively induce current in the other magnetically coupledcoil connected to the load. Examples of conventional wireless powertransfer systems may be found in the following references, thedisclosures of each of which are hereby incorporated entirely herein byreference: the paper by Chen et al., “A Study of Loosely Coupled Coilsfor Wireless Power Transfer,” IEEE Transactions on Circuits andSystems—II: Express Briefs, V. 57, No. 7, pp. 536-540 (July 2010); thepaper by Waters et al., “Adaptive Impedance Matching for MagneticallyCoupled Resonators,” PIERS Proceedings, Moscow, Russia, pp. 694-701(Aug. 19-23, 2012); the paper by Cannon et al., “Magnetic ResonantCoupling as a Potential Means for Wireless Power Transfer to MultipleSmall Receivers,” IEEE Transactions on Power Electronics, V. 24, No. 7,pp. 1819-1825 (July 2009).

SUMMARY

Implementations of a wireless power transmission system may include apower source coupled with a first wireless power transmission (WPT)system and a load coupled with a second WPT system including a sensecircuit. The second WPT system, using the sense circuit, may beconfigured to dynamically tune a resonance of the second WPT system withthe first WPT system to a desired resonance frequency value to allowtransfer of a desired voltage or a desired power to the load. Thedesired resonance frequency value may be less than a maximum possibleresonance frequency value. The first WPT system may be capable oftransmitting more voltage or more power than the second WPT system orthe load can receive without inducing damage to the second WPT system orthe load.

Implementations of WPT systems may include one, all, or any of thefollowing:

The sense circuit may be configured to tune a resonance of the secondWPT system with the first WPT system through adjusting a frequencytransmitted by the first WPT system or a frequency received by thesecond WPT system.

The sense circuit may be configured to tune a resonance of the secondWPT system with the first WPT system through adjusting a capacitance ofthe second WPT system.

The sense circuit may be configured to adjust the capacitance of thesecond WPT system through adjusting a voltage bias of a voltagedependent capacitor included in the second WPT system using the sensecircuit.

The second WPT system may include at least one stage including at leasta first coil and the sense circuit may be configured to tune a resonanceof the second WPT system with the first WPT system through detuning ofthe at least first coil to the desired resonance frequency value.

Implementations of WPT systems may utilize implementations of a methodof wireless power transmission. The method may include providing a powersource coupled with a first WPT system, providing a load coupled with asecond WPT system, and tuning a resonance of the second WPT system withthe first WPT system to a desired resonance frequency value to allowtransfer of a desired voltage and a desired power to the load. Thedesired resonance frequency value may be less than a maximum possibleresonance level. The first WPT system may be capable of transmittingmore voltage or more power than the second WPT system or the load canreceive without inducing damage to the second WPT system or the load.

Implementations of a method of wireless power transmission may includeone, all, or any of the following:

Tuning a resonance of the second WPT system with the first WPT systemmay further include adjusting a frequency transmitted by the first WPTsystem or a frequency received by the second WPT system.

Tuning a resonance of the second WPT system with the first WPT systemmay further include adjusting a capacitance of the second WPT system.

The method may further include providing a second load coupled with athird WPT system and tuning a resonance of the third WPT system with thefirst WPT system to a desired resonance frequency value to allowtransfer of a desired voltage or a desired power to a load. The desiredresonance frequency value may be less than a maximum possible resonancefrequency value. The first WPT system may be capable of transmittingmore voltage or more power than the third WPT system or the second loadcan receive without inducing damage to the third WPT system or thesecond load.

The method may further include providing a second load coupled with athird WPT system where the third WPT system and second load are adaptedto operate at the maximum possible resonance frequency value withoutinducing damage to the third WPT system or the second load.

The second WPT system may include a sense circuit and tuning theresonance of the second WPT system with the first WPT system may furtherinclude tuning using the sense circuit.

Tuning using the sense circuit may further include tuning by adjusting afrequency transmitted by the first WPT system or a frequency received bythe second WPT system using the sense circuit.

Tuning the sense circuit may further include tuning by adjusting acapacitance of the second WPT system using the sense circuit.

Adjusting a capacitance of the second WPT system using the sense circuitmay further include adjusting a voltage bias of a voltage dependentcapacitor using the sense circuit.

The second WPT system may include a two stage resonator including afirst coil and a second coil and tuning the resonance of the second WPTsystem with the first WPT system may further include detuning of thefirst coil or the second coil to the desired resonance frequency value.

The second WPT system may include a single stage resonator including afirst coil and tuning the resonance of the second WPT system with thefirst WPT system further includes detuning of the first coil to thedesired resonance frequency value.

Tuning the resonance of the second WPT system with the first WPT systemmay further include tuning after completion of an initial wireless powertransmission through transmitting a feedback signal to the first WPTsystem to tune a resonance of the first WPT system or tuning theresonance of the second WPT system using a sense circuit included in thesecond WPT system.

Implementations of WPT systems may utilize implementations of a methodof wireless power transmission. The method may include providing a powersource coupled with a first WPT system, providing a load coupled with asecond WPT system, and dynamically tuning a resonance of the second WPTsystem with the first WPT system to a desired resonance frequency valueis less than a maximum possible resonance frequency value. The desiredresonance frequency value may be less than a maximum possible resonancefrequency value. The first WPT system may be capable of transmittingmore voltage or more power than the second WPT system or the load canreceive without inducing damage to the second WPT system or the load.

Implementations of a method of wireless power transmission may includeone, all, or any of the following:

Dynamically tuning the resonance of the second WPT system with the firstWPT system may further include tuning after completion of an initialwireless power transmission through transmitting a feedback signal fromthe second WPT system to the first WPT system to tune a resonance of thefirst WPT system.

The method may further include tuning through adjusting a frequencytransmitted by the first WPT system in response to receiving thefeedback signal from the second WPT system.

Dynamically tuning the resonance of the second WPT system with the firstWPT system may further include tuning after completion of an initialwireless power transmission through tuning the resonance of the secondWPT system using a sense circuit included in the second WPT system wherethe sense circuit adjusts a frequency received by the second WPT system,a capacitance of the second WPT system or any combination thereof.

The foregoing and other aspects, features, and advantages will beapparent to those artisans of ordinary skill in the art from theDESCRIPTION and DRAWINGS, and from the CLAIMS.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations will hereinafter be described in conjunction with theappended drawings, where like designations denote like elements, and:

FIG. 1 is a block diagram of a wireless power transmission system;

FIG. 2 is a plot of the magnetic field of a coil of a wireless powertransmission system (WPT);

FIG. 3 is a circuit and block diagram of a portion of a firstimplementation of a WPT;

FIG. 4 is a circuit and block diagram of a portion of a secondimplementation of a WPT;

FIG. 5 is a diagram showing a frequency response of a conventionalresonator with peak resonance at 6.78 MHz;

FIGS. 6A, B, and C are circuit diagrams of components of a firstimplementation of a sense circuit and capacitor array for adjusting thecapacitance of a WPT system;

FIG. 7 is a circuit diagram of components of a sense circuit and systemfor adjusting the voltage bias applied to a voltage dependent capacitorused to adjust the capacitance of a WPT system.

DESCRIPTION

This disclosure, its aspects and implementations, are not limited to thespecific components, assembly procedures or method elements disclosedherein. Many additional components, assembly procedures and/or methodelements known in the art consistent with the intended wireless powertransmission systems (WPT) will become apparent for use with particularimplementations from this disclosure. Accordingly, for example, althoughparticular implementations are disclosed, such implementations andimplementing components may comprise any shape, size, style, type,model, version, measurement, concentration, material, quantity, methodelement, step, and/or the like as is known in the art for such WPTsystems, and implementing components and methods, consistent with theintended operation and methods.

Various implementations of WPT systems and methods of wireless powertransmission utilized by WPT system implementations are disclosed inthis document. These systems and methods may utilize or include one,all, or any of the various components and functions of the systemsoutlined in the references incorporated herein by reference. The systemsdisclosed herein may be near field wireless charging systems.

Referring to FIG. 1, an implementation of a WPT system 2 is illustrated.As illustrated, the system 2 includes a transmission (Tx) side 4 (firstWPT system) and a receiving (Rx) side 6 (second WPT system). A TxResonator is used to transmit power to a loosely magnetically coupledcorresponding Rx Resonator which then provides the power to a ClientDevice Load (load). Depending upon the resonance frequency value betweenthe Tx Resonator and the Rx Resonator, more or less power and/or voltageand/or current can be transmitted to the receiving side 6 and the load.In some WPT system implementations, the potential power and/or voltagethat can be applied to the receiving side 6 may be in excess of thepower and/or voltage which can be carried/handled by the any one or allof the components included in the receiving side 6 or the load itself.In such a situation, if the resonance frequency valueat the frequency ofthe transmitting or receiving side is too high, then too much powerand/or voltage may be provided to the components in the receiving side 6and/or the load, which can induce damage to the components of the WPTsystem and/or the load either in the short or long term.

Conventional WPT systems seek to maximize the resonance frequency valueto ensure that power is transmitted to the receiving side at a maximumefficiency. This is because as the Tx Resonator and the Rx Resonator areonly loosely coupled, it is more difficult to transfer the power and theloss between the resonators is correspondingly higher than in aclosely/tightly coupled system (like a transformer). Because thesesystems seek to operate at a fixed point of maximum resonance, receivingsides/WPT systems that cannot handle the power and/or voltage providedby the transmission side 4 cannot be used with such transmission WPTsystems without the use of external electrical protective components,which increase overall cost and consume space within the systems

Various implementations of WPT systems are disclosed herein that allowthe resonance of the receiving side 6 to be tuned to a desired resonancefrequency value which is less than the maximum resonance frequency valuewhich allows operation at maximum power transfer efficiency. Thiscapability of the system permits receiving WPT system implementations tobe used with transmitting WPT system that are capable of transmittinggreater power/voltage than the receiving WPT system can handle withoutinducing damage to the system. Furthermore, this capability of the WPTsystems may permit multiple types of receiving WPT systems and/or loadsthat operate at different power/voltage requirements to utilize the sametransmitting WPT system without requiring the use of external electricalcomponents to be applied to the receiving WPT system, the load, or boththe WPT system and the load to protect the receiving WPT or the loadfrom damage. In such systems, devices with receiving sides (third WPTsystems) may be used that are designed to handle the full power and/orvoltage from the transmitting side in conjunction with the devices thatrequired tuning protection. As the output power ranges of transmittingWPT systems (power transmitter units, PTUs) can range from about 2 W toabout 70 W, depending on the application, being able to flexibly chargedifferent WPT systems using the same transmitting WPT system may beadvantageous. Furthermore, where the receiving WPT system is included ina biomedical/wearable device such as, by non-limiting example, hearingaids, watches, and other wearable electronic devices, the space requiredto use external electrical components to protect the WPT system and/orthe load may not be available. Since the induced voltage can be as highto tens to hundreds of volts depending on the receiving resonatorcoupling of the devices, damage to the receiving device can occur.

Referring to FIGS. 1 and 2, the Rx Resonator and Tx Resonator utilizedin the system 2 use a square planar coil design that may have themagnetic flux field illustrated in FIG. 2. In other systemimplementations, however, circular, ellipsoidally shaped, or otherclosed shaped coils could be used, including planar coils, as couldspiral coils formed in any closed shape. Various three dimensionallyshaped coil designs may also be employed in various implementations,such as, by non-limiting example, bowl-shapes, cuboidal designs, conical(right or oblique) designs, parallelepiped designs, and other regular orirregular three-dimensional shaped designs. In various implementations,including those illustrated herein the resonator may be spiral inductorwith N turns in combination with an external capacitor. A wide varietyof electrical components could be used as part of the system 2 includingrectifiers, DC to DC converters, matching circuits, power amplifiers,and voltage control circuits. As will be described in more detailherein, the transmitting side 4 and the receiving side 6 may includevarious master control (MCU) units and signaling units that allow forwireless communication between the transmitting side 4 and the receivingside 6.

Referring to FIG. 3 a first implementation of a WPT system 8 isillustrated. As illustrated, the system 8 includes a transmitter 10(first WPT system) which is coupled to a power supply (not shown). Thereceiving side of the system 8 includes two stages, Receiver 1 StageResonator (first stage 12) and Receiver 2^(nd) Stage Resonator (secondstage 14). These stages are electrically coupled together through coilsL_(RX) on each stage to allow for transmission/conditioning of the powersignal received from the transmitter 10 prior to the power being appliedto the load R_(L). In various implementations, the first stage 12 coilis a spiral inductor with N turns and the second stage 14 coil is aspiral inductor with N/2 turns that are closely coupled. As illustrated,the first stage 12 includes a voltage dependent capacitor 16 whichcreates a capacitance of the first stage C_(TUNE) in combination withreceiving capacitor C_(RX). Any of a wide variety of voltage dependentcapacitors could be used in various implementations. In particularimplementations, the voltage dependent capacitors could be a passivetunable integrated circuit (PTIC) like that manufactured by ONSemiconductor of Phoenix, Ariz. An example of various implementations ofPTICs can be found in the data sheet included herewith as Appendix A,the disclosure of which is hereby incorporated entirely herein byreference. In other implementations, the voltage dependent capacitorcould not be used, and as will be described hereafter, a bank or arrayof capacitors coupled to switches may be used to adjust the capacitanceof the first stage 12.

A capacitor tuning control 18 is included that is designed to adjust thecapacitance of the voltage dependent capacitor 16 and, accordingly,adjust the resonance frequency value of the first stage 12. Because theresonance frequency value of the first stage 12 is adjustable throughthe adjustment of the capacitance of the first stage 12, thepower/voltage received by/available to the second stage 14 and appliedto the load will adjust correspondingly since the stages are closelycoupled. Various implementations of capacitor tuning control circuitswill be described hereafter. Additional stages (3, 4, or more.) could beincluded in various system implementations. Both the resonance of theseand the second stage may be similarly tuned using the principlesdisclosed herein in various implementations.

Referring to FIG. 4, a second implementation of a WPT system 20 isillustrated. As illustrated, the system 20 includes a single stage 22 onthe receiving side (Receiver 1 Stage Resonator) which directly couplesthe coil L_(RX) to the load R_(L). A voltage dependent capacitorC_(TUNE) 24 is included which is capable of altering the capacitance ofthe stage 22 in response to a bias voltage signal applied by CapacitorTuning Control 26, which may be any implementation of capacitor tuningcontrol circuit disclosed herein. Through adjustment of the capacitanceof the single stage 22, the resonance frequency value of the coil L_(RX)of the 22 with the transmitter 27 is tuned to a desired resonancefrequency value and the amount of power/voltage being applied to theload is correspondingly directly adjusted.

Implementations disclosed herein have discussed adjusting thecapacitance of the receiving WPT system (second WPT system, or third,fourth, or more WPT systems) to tune the resonance frequency value ofthe receiving WPT system to a desired resonance level. In otherimplementations, the frequency of transmitting side or receiving side orboth the transmitting and receiving side of the WPT system may beadjusted to tune the resonance frequency value of the system. Byadjusting the resonance frequency value is meant adjusting the system'sability to receive/resonate with a particular frequency. Referring toFIG. 5, a graph of the received voltage by frequency in a conventionalcoil implementation is illustrated. As illustrated, there is a resonantfrequency for the coil that produces a maximum resonance frequency valueand, correspondingly permits maximum transmission of voltage between thetransmitting coil and receiving coil. In this system, the resonantfrequency is about 6.78 MHz, though in various other systemimplementations, other frequencies could be used, such as, bynon-limiting example, about 13.56 MHz, about 27.12 MHz, about 2.4 GHz,and any other frequency capable of creating a resonant power transferbetween a transmitting side and receiving side of a WPT system.

FIG. 5 illustrates how, on either side of the resonant frequency voltagemaximum, the frequency received by the receiving side of the WPT systemand/or transmitted by the transmitting side of the WPT system can beadjusted to reduce the voltage being transmitted. Since, as can beobserved, the relationship between the voltage and the frequency issecond order with respect to frequency, a small increase or decrease inthe frequency from the resonant frequency can result in a large changein the transmitted voltage initially while larger changes result insmaller changes in the transmitted voltage. In various implementations,frequency tuners and other frequency adjusting devices and systems maybe employed to adjust the frequency behavior of the transmitting,receiving, or both the receiving side and transmitting side of the WPTsystem to achieve a desired resonance frequency value. Since thefrequency changes move the frequency away from the resonant frequency,the process of adjusting the frequency being received and/or transmittedmay be referred to as “detuning” the frequency and, correspondingly, theresonance frequency value of the WPT system. Through detuning of theresonance frequency, the voltage and/or power applied to the load isadjusted to prevent damage to the load or the components of thereceiving side of the WPT system.

Other system parameters may also be adjusted to tune the resonancebeyond capacitance including, by non-limiting example, qualitycoefficients, geometries of the receiving coil, and any other parametercapable of changing the resonance frequency value between thetransmitting and receiving sides of a WPT system.

In various WPT system implementations, a sense circuit may be includedin the receiving side of the WPT system (second WPT system). The sensecircuit is designed to measure the voltage and/or power being applied tothe receiving side (whether single stage, first stage, or othermulti-stage) and then change an operating parameter of the receivingside to tune the resonance frequency value to a desired or calculatedtarget value that will prevent inducing damage to the receiving sidecomponents and/or the load. Referring to FIG. 6B, an implementation of aportion of a sense circuit 28 is illustrated which includes twocomparators 30, 32. The first comparator 30 receives the incomingvoltage being received from the transmitting side (V_(resntr)) andcompares it to a high threshold voltage (Thresh_Hi) and outputs theresult. Likewise, the second comparator 32 receives the incoming voltageand compares it to a low threshold voltage (Thresh_Lo) and outputs theresult. The threshold voltages may, in various implementations, be setby an on-chip reference circuit or other threshold voltage generatingcircuit. The high threshold voltage is set at a level designed toprevent damage to the components of the receiving side and/or the load.In some implementations, it may be set to be just below the value of thedevice reliability voltage limit for the device on a chip associatedwith the receiving side or load. The low threshold voltage may be set ata desired value to allow the sense circuit to tune the resonance toincrease the voltage being received from the transmitting side.

The outputs of the first and second comparators 30, 32 may be receivedby an N-bit Counter/Decoder 34 like that illustrated in FIG. 6C. Theoutputs may be processing using a clock or stored through use of one ormore latches or even fuses in various implementations. In theimplementation illustrated in FIG. 6C, the N-bit Counter/Decoder 34stores/transmits the received output(s) and provides N bits of outputthat correspond with the received output(s). Referring to FIG. 6A, animplementation of an array of capacitors 36, 38 coupled in parallel isillustrated. As illustrated, each of the capacitors 36, 38 is coupled inseries with switches 40, 42, respectively. Since the capacitor array iscoupled to the coil LR, using the switches to connect/disconnect thecapacitors 36, 38 changes the capacitance of the receiving side in aratio of CR across CR. The change in capacitance varies the frequency ofthe coil LR, and the resonance of the coil with the transmitting coil.Since in various implementations, the switches may be each be coupled toan output of the N-bit Counter/Decoder 34 of FIG. 6C, as the N outputschange, the various switches open and close correspondingly. In thisway, the capacitance of the receiving side (or a stage of the receivingside) can be altered to tune the resonance frequency value of thereceiving side or stage. In such implementations, a voltage dependentcapacitor is not used, but the sense circuit uses the incoming voltageto adjust the capacitance of the receiving side accordingly to achieve adesired resonance frequency value (and, correspondingly, a desiredvoltage/power value).

Referring to FIG. 7, an implementation of a sense circuit 44 isillustrated adjacent to an N-bit Counter/Encoder 46 to which the outputswould be electrically coupled, similarly to the implementationillustrated in FIGS. 6B and 6C. As previously described, the sensecircuit 44 monitors the incoming voltage V_(resntr) and compares it to ahigh and low threshold value using comparators 48 and 50, respectively.The outputs of the comparators are then processed by the N-bitCounter/Encoder 46 which is coupled with an array of constant currentsources 52, 54 each coupled in series with an array of switches 56, 58.The array of constant current sources 52, 54 is coupled to an impedancenetwork 56 that together forms a decoder controlled bias voltagegenerator which assists in creating a voltage output that becomes thebias voltage applied to voltage dependent capacitor 62. As voltagedependent capacitor 62 is coupled with the receiving side circuitry, asthe bias voltage changes, the capacitance of the receiving side changes,allowing for tuning of the resonance frequency value to one that willprovide the desired voltage levels for use by the load.

While the sense circuit implementations illustrated in FIGS. 6A-C and 7are involved in adjusting the capacitance to tune the resonancefrequency value of a receiving side, sense circuit implementations couldbe used in combination with frequency tuning circuitry to change thefrequency received and/or transmitted to also tune the resonancefrequency value. Such sense circuit implementations could be included inthe MCU & Out of Band Signaling components of the receiving side 6 andtransmitting side 4 illustrated in FIG. 1. In such implementations,wireless transmissions containing a feedback signal from the receivingside 6 may be received by the transmitting side and the frequency, forexample, adjusted accordingly in response to tune the resonancefrequency value. Likewise, in a feedforward control manner, wirelesstransmissions containing a feedforward signal from the transmitting side4 could be sent to the receiving side 6 so the receiving side 6 canadjust the frequency, capacitance, or frequency and capacitance of thereceiving side 6 in response to receiving the feedforward signal. A widevariety of implementations are possible using the principles disclosedherein.

Although in various implementations, those that adjust capacitance ofthe receiving side or frequency of the receiving side are illustrated,through use of feedback signals, the frequency or other parameterscontrolling the power and/or voltage being transmitted by thetransmitting side of the WPT systems may also be adjusted. However, invarious implementations, it may be simpler to manage thefrequency/capacitance/or other power or voltage adjusting parameter onthe receiving side since the receiving side is typically the devicedesigned to work with the transmitting charging station. Such atechnique may allow the charging station design to be essentiallyuniversal while each device manages its resonance levels with thecharging station to charge itself without inducing damage to itscomponents.

Various WPT systems like those disclosed herein may utilize variousimplementations of a method of wireless power transmission. The methodmay include providing a power source coupled with a first WPT system(transmitting side) and providing a load coupled with a second WPTsystem (receiving side). The method may also include tuning a resonanceof the second WPT system with the first WPT system to a desiredresonance level to allow transfer of a desired voltage or a desiredpower to the load. The desired resonance level may be less than amaximum possible resonance level. The first WPT system may be capable oftransmitting more voltage and/or more power than the second WPT systemand/or the load can receive without inducing damage to the second WPTsystem or the load. In various implementations, the tuning may bedynamically done, meaning that it is controlled using a sense circuit orother system/method of automatically altering/tuning the resonancefrequency value of the second WPT system like those disclosed herein. Inothers, the tuning may be manually done by a user manually selecting aresonance level through a selector switch or other manually set variableon the transmitting side or receiving side designed to ensure that thepower/voltage resulting from the frequency being transmitted/receivedwill not damage the receiving device. In various implementations, thetuning process may be referred to a detuning process since the tuningprocess moves the resonance frequency value away from the maximumresonance frequency value.

In various method and system implementations, no a priori or systemcalculated/detected value(s) of the maximum resonance frequency valuemay need to be known by the receiving side for the system to tune theresonance frequency value to find an operating point at which thedesired voltage and/or power level are reached. Instead, the system, onwakeup or when encountering the signal from a transmitting side, may usethe sense circuit or other control circuitry to tune the resonance untilthe desired voltage/and or power level are reached. In variousimplementations, the system may power up with the various controlcircuitry set to non-resonant values for safety purposes, and thensubsequently adjusted. In various implementations, on power down, thecontrol circuitry may also be reset to non-resonant values for safetypurposes.

In various method implementations, the tuning of the resonance frequencyvalue may take place after an initial wireless power transmission hastaken place (which may or may not have passed through the load) betweenthe transmitting side and the receiving side. In other implementations,both the capacitance and the frequency (frequency being received) of thereceiving side may be tuned to adjust the resonance frequency value. Inother implementations, the tuning of the resonance frequency value maybe take place in response to feedback from the load. In theseimplementations, in response to the load indicating it needs more orless power or voltage, the control circuitry (sense circuit in someimplementations) tunes the resonance of the receiving side coil to adesired/calculated level.

In places where the description above refers to particularimplementations of WPT systems and implementing components,sub-components, methods and sub-methods, it should be readily apparentthat a number of modifications may be made without departing from thespirit thereof and that these implementations, implementing components,sub-components, methods and sub-methods may be applied to other WPTsystems.

What is claimed is:
 1. A method of wireless power transmission, themethod comprising: providing a power source coupled with a firstwireless power transmission (WPT) system; providing a load coupled witha second WPT system; detuning a resonance of the second WPT system withthe first WPT system to a desired resonance frequency value to allowtransfer of one of a desired voltage and a desired power to the loadwithout damaging one of the second WPT system and the load; wherein thedesired resonance frequency value is less than a maximum possibleresonance level; and wherein the first WPT system is capable oftransmitting one of more voltage and more power than one of the secondWPT system and the load can receive without inducing damage to one ofthe second WPT system and the load.
 2. The method of claim 1, whereintuning the resonance of the second WPT system with the first WPT systemfurther comprises adjusting one of a frequency transmitted by the firstWPT system and a frequency received by the second WPT system.
 3. Themethod of claim 1, wherein tuning the resonance of the second WPT systemwith the first WPT system further comprises adjusting a capacitance ofthe second WPT system.
 4. The method of claim 1, further comprising:providing a second load coupled with a third WPT system; tuning aresonance of the third WPT system with the first WPT system to a desiredresonance frequency value to allow transfer of one of a desired voltageand a desired power to the second load; wherein the desired resonancefrequency value is less than a maximum possible resonance frequencyvalue; and wherein the first WPT system is capable of transmitting oneof more voltage and more power than one of the third WPT system and thesecond load can receive without inducing damage to one of the third WPTsystem and the second load.
 5. The method of claim 1, furthercomprising: providing a second load coupled with a third WPT systemwherein the third WPT system and second load are adapted to operate atthe maximum possible resonance frequency value without inducing damageto the third WPT system and the second load.
 6. The method of claim 1,wherein the second WPT system comprises a sense circuit and tuning theresonance of the second WPT system with the first WPT system furthercomprises tuning using the sense circuit.
 7. The method of claim 6,wherein tuning using the sense circuit further comprises tuning byadjusting one of a frequency transmitted by the first WPT system and afrequency received by the second WPT system using the sense circuit. 8.The method of claim 6, wherein tuning using the sense circuit furthercomprises tuning by adjusting a capacitance of the second WPT systemusing the sense circuit.
 9. The method of claim 8, wherein adjusting acapacitance of the second WPT system using the sense circuit furthercomprises adjusting a voltage bias of a voltage dependent capacitorusing the sense circuit.
 10. The method of claim 1, wherein the secondWPT system comprises a two stage resonator comprising a first coil and asecond coil and tuning the resonance of the second WPT system with thefirst WPT system further comprises detuning of one of the first coil andthe second coil to the desired resonance frequency value.
 11. The methodof claim 1, wherein the second WPT system comprises a single stageresonator comprising a first coil and tuning the resonance of the secondWPT system with the first WPT system further comprises detuning of thefirst coil to the desired resonance frequency value.
 12. The method ofclaim 1, wherein tuning the resonance of the second WPT system with thefirst WPT system further comprises tuning after completion of an initialwireless power transmission through one of: transmitting a feedbacksignal to the first WPT system to tune a resonance of the first WPTsystem; and tuning the resonance of the second WPT system using a sensecircuit comprised in the second WPT system.
 13. A method of wirelesspower transmission, the method comprising: providing a power sourcecoupled with a first wireless power transmission (WPT) system; providinga load coupled with a second WPT system; dynamically detuning aresonance of the second WPT system with the first WPT system to adesired resonance frequency value to allow transfer of one of a desiredvoltage and a desired power to the load without damaging one of thesecond WPT system and the load; wherein the desired resonance frequencyvalue is less than a maximum possible resonance frequency value; andwherein the first WPT system is capable of transmitting one of morevoltage and more power than one of the second WPT system and the loadcan receive without inducing damage to one of the second WPT system andthe load.
 14. The method of claim 13, wherein dynamically tuning theresonance of the second WPT system with the first WPT system furthercomprises tuning after completion of an initial wireless powertransmission through transmitting a feedback signal from the second WPTsystem to the first WPT system to tune a resonance of the first WPTsystem.
 15. The method of claim 14, further comprising tuning throughadjusting a frequency transmitted by the first WPT system in response toreceiving the feedback signal from the second WPT system.
 16. The methodof claim 13, wherein dynamically tuning the resonance of the second WPTsystem with the first WPT system further comprises tuning aftercompletion of an initial wireless power transmission through tuning theresonance of the second WPT system using a sense circuit comprised inthe second WPT system wherein the sense circuit adjusts one of afrequency received by the second WPT system, a capacitance of the secondWPT system; and any combination thereof.
 17. A wireless powertransmission system comprising: a power source coupled with a firstwireless power transmission (WPT) system; a load coupled with a secondWPT system comprising a sense circuit; wherein the second WPT system,using the sense circuit, is configured to dynamically detune a resonanceof the second WPT system with the first WPT system to a desiredresonance frequency value to allow transfer of one of a desired voltageand a desired power to the load without damaging one of the second WPTsystem and the load; wherein the desired resonance frequency value isless than a maximum possible resonance frequency value; and wherein thefirst WPT system is capable of transmitting one of more voltage and morepower than one of the second WPT system and the load can receive withoutinducing damage to one of the second WPT system and the load.
 18. Thesystem of claim 17, wherein the sense circuit is configured to tune aresonance of the second WPT system with the first WPT system throughadjusting one of a frequency transmitted by the first WPT system and afrequency received by the second WPT system.
 19. The system of claim 17,wherein the sense circuit is configured to tune a resonance of thesecond WPT system with the first WPT system through adjusting acapacitance of the second WPT system.
 20. The system of claim 19,wherein the sense circuit is configured to adjust the capacitance of thesecond WPT system through adjusting a voltage bias of a voltagedependent capacitor comprised in the second WPT system using the sensecircuit.
 21. The system of claim 17, wherein the second WPT systemcomprises at least one stage comprising at least a first coil and thesense circuit is configured to tune a resonance of the second WPT systemwith the first WPT system through detuning of the at least first coil tothe desired resonance frequency value.